Efficient Synthesis of Poly(2-ethyl-3-methylindole)

Poly[2-(2-chloro-1-methylbut-2-en-1-yl)aniline] in polyphosphoric acid at 140–150°C undergoes intramolecular cyclization to produce previously unknown indole polymer, poly(2-ethyl-3-methyl-1H-indole), with 1,5-linkage of monomer units.